On 7/26/2023 7:54 PM, Sean Christopherson wrote: > On Wed, Jul 26, 2023, Nikunj A. Dadhania wrote: >> On 7/24/2023 10:30 PM, Sean Christopherson wrote: >>>> /proc/<qemu pid>/smaps >>>> 7f528be00000-7f5c8be00000 rw-p 00000000 00:01 26629 /memfd:memory-backend-memfd-shared (deleted) >>>> 7f5c90200000-7f5c90220000 rw-s 00000000 00:01 44033 /memfd:rom-backend-memfd-shared (deleted) >>>> 7f5c90400000-7f5c90420000 rw-s 00000000 00:01 44032 /memfd:rom-backend-memfd-shared (deleted) >>>> 7f5c90800000-7f5c90b7c000 rw-s 00000000 00:01 1025 /memfd:rom-backend-memfd-shared (deleted) >>> >>> This is all expected, and IMO correct. There are no userspace mappings, and so >>> not accounting anything is working as intended. >> Doesn't sound that correct, if 10 SNP guests are running each using 10GB, how >> would we know who is using 100GB of memory? > > It's correct with respect to what the interfaces show, which is how much memory > is *mapped* into userspace. > > As I said (or at least tried to say) in my first reply, I am not against exposing > memory usage to userspace via stats, only that it's not obvious to me that the > existing VMA-based stats are the most appropriate way to surface this information. Right, then should we think in the line of creating a VM IOCTL for querying current memory usage for guest-memfd ? We could use memcg for statistics, but then memory cgroup can be disabled and so memcg isn't really a dependable option. Do you have some ideas on how to expose the memory usage to the user space other than VMA-based stats ? Regards, Nikunj
